The following patents illustrate prior art which may be relevant to the invention disclosed and claimed herein, but which fail to teach the improvement disclosed and claimed herein:    1. U.S. Pat. No. 4,275,670 issued to Dreyer for “Seed Drill Mounting Arrangement”;    2. U.S. Pat. No. 4,407,207 issued to Dreyer for “Drill Having Disk Furrow Openers”;    3. U.S. Pat. No. 5,802,995 issued to Baugher et al. for “Planting Unit”;    4. U.S. Pat. No. 6,308,645 issued to Newkirk et al. for “Seeding Machine with Bulk Seed Supply Container and Independent, Opener-Mounted Metering Devices”;    5. U.S. Pat. No. 4,422,392 issued to Dreyer et al. for “Seed Drill with Disk-Type Furrow Openers”;    6. U.S. Pat. No. 4,117,788 issued to Whitehead for “Seed Drill Including Discs Driven by Ground Wheel Drive”;    7. U.S. Pat. No. 4,366,760 issued to Dreyer for “Seed Drill”; and,    8. Great Britain Patent #1,218,785 issued to Moore et al. for “Improved Method and Means for Agricultural Seeding.”
Furthermore, other patents of interest may include U.S. Pat. No. 2,605,017; U.S. Pat. No. 2,552,810 and U.S. Pat. No. 2,406,702